With the recent spread of measuring instruments and medical instruments which utilize radiation, persons who operate them and doctors and technical experts who conduct radiotherapy of cancer are always confronted with injury risk incurred by exposure to radiation. With an increase of the utilization of airplanes, carcinogenesis risk incurred by exposure to cosmic rays of aircrews and passengers is in question. In addition, carcinogenesis risk incurred by exposure to a slight amount of radiation of persons who undergo a medical examination by utilization of X-ray CT or the like is in question. On the other hand, it is pointed out that common persons may possibly be injured by exposure to radiation owing to an accident or terrorism connected with an atomic power station. Therefore, the development of a radiation protection drug for overcoming the risk of health disorders caused by exposure to radiation is an important social problem. However, very few radiation protection drugs for preventing and treating health disorders caused by exposure to radiation have been put to practical use (in the U.S.A., amifostine has been approved for preventing xerostomia in cancer radiotherapy in head-neck; J. Clin. Oncol. 18, 339 (2000)), and the development of a novel radiation protection drug is desired. Various aminothiols have been reported as radiation protection drugs for effective protection against health disorders caused by exposure to radiation (non-patent document 1). Shikita et al. have reported the effectiveness of heat-killed lactobacillus preparations as a radiation protection drug (Radiat. Res. 125, 293 (1991)), and Kagiya et al. have reported chromanol glycoside (patent document 1). The present inventors have reported the utilization of edaravone, a cerebral neuroprotective drug, as a radiation protection drug (patent document 2 and non-patent document 2), the protective effect of nitroxides on radiation (non-patent document 3), and heat-treated yeasts containing minerals (patent document 3).
Patent Document 1: JP 10-72356 A
Patent Document 2: Japanese Patent Application No. 2002-67739
Patent Document 3: Japanese Patent Application No. 2005-379185
Non-Patent Document 1: Tsutomu Sugawara et al., “Houshasen to Igaku”, Kyoritsu Shuppan Co., Ltd., 1986
Non-Patent Document 2: J. Radiat. Res, 45, 319-323 (2004)
Non-Patent Document 3: Free Radic. Biol. Med., 40, 1170-1178 (2006)